LESSON 1: Basic Chemistry
Atoms & Ions | Chemical Bonding | Water | Acid & Bases | Organic Compounds | Carbohydrates | Lipids | Proteins | Enzymes | Nucleic Acids | ATP


Hooking Stuff Together

Chemical bonds are formed when the electrons in an atom interact with the electrons in another atom. This allows for the formation of more complex molecules.

There are 3 types of chemical bonds:

  Bond Strength Description Example
Covalent Strong Two atoms share electrons. Bonding of Oxygen and Hydrogen in H2O
Ionic Moderate Oppositely charged ions are attracted to each other. Bond between Na+ and Cl- in salt.
Hydrogen Weak Forms between oppositely charges portions of covalently bonded hydrogen atoms. Bonds between water molecules.


These strong bonds form when two atoms share electrons.

Sometimes the electrons in an atom get shared. It's much like when you were a kid and got to sleep over at a friends house. Your friends parents were in charge of you both for one night and the next night you would sleep over at your house and your own parents would be in charge. This sharing of responsibility is functionally similar to the way covalent bonding works.

Normally this sharing is an equal proposition. Sometimes it's not equal (but that gets us into hydrogen bonding discussed below.)


Atoms gain or lose electron (opposites attract)

Ions have positive or negative charges. In dating situations, you may know that sometimes opposites attract. In Chemistry, opposites ALWAYS attract. This forms an ionic bond between two atoms.


Weakest bond between atoms

Occurs in molecules that have covalent bonds. Sometimes the electrons are not equally shared; one atom tends to have an electron more often than the other atom. In this situation one atom of the molecule becomes partly negative and the other then becomes partly positive.

Now we have positive and negative things becoming attracted to each other. (remember ionic bonds?) This is especially common between water molecules.